The 2.8.2 release of DragonFly BSD is now available, featuring significant advances in multi-processor performance based on DragonFly's signature soft token locks. It also includes many feature advancements including: pf from OpenBSD 4.2, the Wifi stack from FreeBSD and DataMapper from NetBSD (with significant enhancements). This release also marks the return of the GUI image. See the release notes for full details.

At reading the teaser in Opera's feeds reader, I thought "how many BSD variants are there?". Why? Because of this:
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DragonFly BSD is now available [...] includes many feature advancements including: pf from OpenBSD 4.2, the Wifi stack from FreeBSD and DataMapper from NetBSD

The landscape seems crowded to me and since as I'm not into BSD systems, I thought I'd better ask the question here. "

FreeBSD, NetBSD, OpenBSD, and DragonflyBSD are the most popular "flavors." There are other flavors, but you'll find that these four make up the bulk of *BSD systems.

These flavors are commonly confused with Linux distributions. Unlike Linux distributions, which all use the same kernel and really only differ in the userland tools they provide, each "flavor" of *BSD has its own kernel, own base system, own userland tools, and own package management system. Each *BSD flavor its its own full-featured OS.

All of the current *BSD's are based on the original 4.4-BSD operating system. FreeBSD and NetBSD are direct ports, while OpenBSD and DragonflyBSD are forks of NetBSD and FreeBSD respectively. Since they share the same heritage, they also share a lot of code which makes porting tools easy. This is why you see DragonflyBSD using tools from other flavors and visa versa.